Cardiorespiratory responses to exercise in acute hypoxia, hyperoxia and normoxia

Peltonen, Jari; Tikkanen, Heikki; Rusko, Heikki

doi:10.1007/s004210100411

Cited by 80 publications

(83 citation statements)

References 34 publications

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“…[2][3][4] In the present study, the delta VO 2 / delta work rate was decreased under hypoxia. This finding was in accordance with that of a previous report showing that delta VO 2 / delta work rate was decreased under acute moderate hypoxia.…”

Section: Discussionsupporting

confidence: 55%

“…Although in previous studies researchers investigated the acute effect of hypoxia on the CO response during maximal and/or submaximal exercise at moderate altitude (corresponding to 2500 -3000 m), [2][3][4]16,17) in only three studies the SV response was examined during exercise. However, in those investigations, SV was measured at only several time-points during exercise.…”

Section: )mentioning

confidence: 99%

“…However, in those investigations, SV was measured at only several time-points during exercise. 3,4,17) Therefore, whether acute hypoxia at moderate altitude may alter the SV response during exercise has not been fully investigated.CO measurement by the impedance method has been improved and can be used to continuously monitor SV, andFrom the …”

mentioning

confidence: 99%

“…Training at moderate altitude (corresponding to 2000 -3000 m) is associated with relatively severe hypoxemia during submaximal and maximal exercise, 1) and acute hypoxia of this level decreases VO 2 max as well as exercise capacity. [2][3][4] Thus, hypoxia at moderate altitude limits training intensity, which leads to relative deconditioning in elite athletes, although endurance athletes often use hypoxic training to improve sea-level performance. 5) Because VO 2 is the product of cardiac output (CO) and the arterio-venous oxygen content difference (C(a-v)O 2 ), a decrease in VO 2 max at maximal exercise may be due to a decrease of either factor, or both.…”

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confidence: 99%

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Effects of Acute Hypoxia at Moderate Altitude on Stroke Volume and Cardiac Output During Exercise

et al. 2010

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SummaryIt has been unclear how acute hypoxia at moderate altitude affects stroke volume (SV), an index of cardiac function, during exercise. The present study was conducted to reveal whether acute normobaric hypoxia might alter SV during exercise.Nine healthy male subjects performed maximal exercise testing under normobaric normoxic, and normobaric hypoxic conditions (O 2 : 14.4%) in a randomized order. A novel thoracic impedance method was used to continuously measure SV and cardiac output (CO) during exercise.Acute hypoxia decreased maximal work rate (hypoxia; 247 ± 6 [SE] versus normoxia; 267 ± 8 W, P < 0.005) and VO 2 max (hypoxia; 2761 ± 99 versus normoxia; 3039 ± 133 mL/min, P < 0.005). Under hypoxic conditions, SV and CO at maximal exercise decreased (SV: hypoxia; 145 ± 11 versus normoxia; 163 ± 11 mL, P < 0.05, CO: hypoxia; 26.7 ± 2.1 versus normoxia; 30.2 ± 1.8 L/min, P < 0.05). In acute hypoxia, SV during submaximal exercise at identical work rate decreased. Furthermore, in hypoxia, 4 of 9 subjects attained their highest SV at maximal exercise, while in normoxia, 8 of 9 subjects did.Acute normobaric hypoxia attenuated the increment of SV and CO during exercise, and SV reached a plateau earlier under hypoxia than in normoxia. Cardiac function during exercise at this level of acute normobaric hypoxia might be attenuated. (Int Heart J 2010; 51: 170-175) Key words: Normobaric hypoxia, Cardiac output, Oxygen uptake, Exercise testing D uring ascent to a moderate to high altitude, individuals are exposed to progressive decreases in atmospheric pressure that lead to a reduction in inspired, alveolar, and arterial oxygen pressures. Training at moderate altitude (corresponding to 2000 -3000 m) is associated with relatively severe hypoxemia during submaximal and maximal exercise, 1) and acute hypoxia of this level decreases VO 2 max as well as exercise capacity.2-4) Thus, hypoxia at moderate altitude limits training intensity, which leads to relative deconditioning in elite athletes, although endurance athletes often use hypoxic training to improve sea-level performance. 5) Because VO 2 is the product of cardiac output (CO) and the arterio-venous oxygen content difference (C(a-v)O 2 ), a decrease in VO 2 max at maximal exercise may be due to a decrease of either factor, or both.Acute hypoxia may induce abnormalities in cardiac function and redistribution of CO not only at rest but also during exercise. In an animal study, CO at rest increased during acute severe hypoxia (FiO 2 10% and 5%), and blood flow to all organs increased except for the skin and muscle.6) In humans under acute hypoxia, heart rate (HR) and CO increase while systemic vascular resistance decreases. 7)Echocardiography also reveals altered mitral flow patterns, suggestive of mild LV diastolic dysfunction.8) Subacute hypoxia (FiO 2 12%, simulating an altitude of approximately 4000 m) induced mild diastolic dysfunction in young healthy individuals. 9)Stroke volume (SV) increases as the work rate increases at low to moderate intensity exercise, ...

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Section: Discussionsupporting

confidence: 55%

Section: )mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Effects of Acute Hypoxia at Moderate Altitude on Stroke Volume and Cardiac Output During Exercise

et al. 2010

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“…Opposite to some authors, in our study the hypoxia VO 2 increased progressively, but this discrepancy may be due to different hypoxia and exercise levels (O 2 10-12%) 18,19 . A potential possibility for VO 2 increase observed in both groups is that probably exercise alters dissociation curve of O 2 -hemoglobin by discharge of phosphate compounds associated to CO 2 releasing increase and acids production by muscles.…”

Section: Isocapnic Hypoxiacontrasting

confidence: 96%

Quimiossensibilidade durante exercício na insuficiência cardíaca: respostas ventilatórias, cronotrópicas e neurohormonais

Moura¹,

Guimarães²,

Pires³

et al. 2010

Arq. Bras. Cardiol.

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Hemoglobin Mass and Aerobic Performance at Moderate Altitude in Elite Athletes

Wehrlin

Marti

Hallén

2016

Advances in Experimental Medicine and Biology

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Fore more than a decade, the live high-train low (LHTL) approach, developed by Levine and Stray-Gundersen, has been widely used by elite endurance athletes. Originally, it was pointed out, that by living at moderate altitude, athletes should benefit from an increased red cell volume (RCV) and hemoglobin mass (Hbmass), while the training at low altitudes should prevent the disadvantage of reduced training intensity at moderate altitude. VO2max is reduced linearly by about 6-8 % per 1000 m increasing altitude in elite athletes from sea level to 3000 m, with corresponding higher relative training intensities for the same absolute work load. With 2 weeks of acclimatization, this initial deficit can be reduced by about one half. It has been debated during the last years whether sea-level training or exposure to moderate altitude increases RCV and Hbmass in elite endurance athletes. Studies which directly measured Hbmass with the optimized CO-rebreathing technique demonstrated that Hbmass in endurance athletes is not influenced by sea-level training. We documented that Hbmass is not increased after 3 years of training in national team cross-country skiers. When athletes are exposed to moderate altitude, new studies support the argument that it is possible to increase Hbmass temporarily by 5-6 %, provided that athletes spend >400 h at altitudes above 2300-2500 m. However, this effect size is smaller than the reported 10-14 % higher Hbmass values of endurance athletes living permanently at 2600 m. It remains to be investigated whether endurance athletes reach these values with a series of LHTL camps.

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Cardiorespiratory responses to exercise in acute hypoxia, hyperoxia and normoxia

Cited by 80 publications

References 34 publications

Effects of Acute Hypoxia at Moderate Altitude on Stroke Volume and Cardiac Output During Exercise

Effects of Acute Hypoxia at Moderate Altitude on Stroke Volume and Cardiac Output During Exercise

Quimiossensibilidade durante exercício na insuficiência cardíaca: respostas ventilatórias, cronotrópicas e neurohormonais

Hemoglobin Mass and Aerobic Performance at Moderate Altitude in Elite Athletes

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